Wednesday, July 26, 2006

Here’s a burning question. On a cool summer day, should you turn off the air conditioning and open the windows? Or will you end up paying more in the long run, since the air conditioning has to work hard to re-cool your place when hot weather returns?

According to Umbra Fisk, environmental advice columnist at Grist Magazine, it’s better for your pocketbook and the planet to shut the AC off.

“The AC will need to expend more energy to re-cool the house than it will to maintain a cool house, but only for a brief period of time,” Fisk writes. “This added energy expenditure over a short period does not justify the constant use of the AC over a longer period. In addition, there are health benefits (physical and mental) to opening your windows.”

Turning off the AC when you leave the house is a good practice even when it’s blazing hot outside. John Peach, an engineer and mathematician, said that leaving the air conditioning running is similar to to leaving your lights on all the time.

“Any time the air conditioning is on, the cool air leaks out of the walls and windows,” he said. “It’s much better to make the air conditioner work hard for an hour to cool your place down after you come home than to have it running – and leaking – for seven or eight hours while you’re at work.”

Peach recommends installing a programmable thermostat to maximize your comfort. “Set the thermostat to turn the air conditioning on about an hour before you’re going to come home. That way you can keep cool without wasting so much energy.”